Establishment of HIV Infection
After entering the body, the viral particle is attracted to a cell with the appropriate CD4 receptor molecules where it attaches by fusion to a susceptible cell membrane or by endocytosis and then enters the cell. The probability of infection is a function of both the number of infective HIV virions in the body fluid which contacts the host as well as the number of cells available at the site of contact that have appropriate CD4 receptors.
Within the cell, the viral particle uncoats from the envelope to releases its RNA. The enzyme product of the pol gene, reverse transcriptase that is bound to the HIV RNA, provides for reverse transcription of RNA to proviral DNA. It is this HIV proviral DNA which is then inserted into host cell genomic DNA by the integrase enzyme. Once the HIV proviral DNA is within the infected cell's genome, it cannot be eliminated or destroyed except by destroying the cell itself. The HIV provirus is then replicated by the host cell. The infected cell can then release virions by surface budding, or infected cells can undergo lysis with release of new HIV virions which can then infect additional cells. Antibodies formed against HIV are not protective, and a viremic state can persist despite the presence of even high antibody titers.
Within the cell, the viral particle uncoats from the envelope to releases its RNA. The enzyme product of the pol gene, reverse transcriptase that is bound to the HIV RNA, provides for reverse transcription of RNA to proviral DNA. It is this HIV proviral DNA which is then inserted into host cell genomic DNA by the integrase enzyme. Once the HIV proviral DNA is within the infected cell's genome, it cannot be eliminated or destroyed except by destroying the cell itself. The HIV provirus is then replicated by the host cell. The infected cell can then release virions by surface budding, or infected cells can undergo lysis with release of new HIV virions which can then infect additional cells. Antibodies formed against HIV are not protective, and a viremic state can persist despite the presence of even high antibody titers.
